With increasing development of scientific technologies, the method for storing documents is changed from filing of paper documents to storage of documents' electronic files. A scanning apparatus is a device for scanning the contents of paper documents into electronic files, which are then stored, processed or spread.
In the early stage, the scanning apparatus can scan one side of the document. For scanning both sides of the document, the document should be manually turned over after one side of the document has been scanned in order to sequentially scan the other side of the document. However, the process of manually turning over the document is troublesome. Recently, a duplex scanning apparatus has been developed for automatically performing a duplex scanning operation to scan both sides of the document.
Hereinafter, the configurations and operating principles of a conventional automatic document feeder will be illustrated with reference to FIG. 1.
FIG. 1 is a schematic side view illustrating an automatic document feeder disclosed in U.S. Pat. No. 7,530,563. As shown in FIG. 1, the automatic document feeder 1 is operated in a standby mode. The automatic document feeder 1 comprises an upper cover 10, a paper-feeding mechanism 11, a transfer module 12, a paper ejecting module 13, a paper input tray 14 and a paper ejecting tray 15. The document D to be scanned is placed on the paper input tray 14. The scanned document D is supported on the paper ejecting tray 15. The paper-feeding mechanism 11 is used for feeding the document D that is placed on the paper input tray 14 into the internal portion of the automatic document feeder 1. The transfer module 12 is used for transporting the document D through the internal portion of the automatic document feeder 1. The paper ejecting module 13 is used for ejecting the document D to the paper ejecting tray 15. As shown in FIG. 1, the automatic document feeder 1 is integrated into a scanning apparatus, which is arranged under the automatic document feeder 1. The operating principles of the scanning apparatus are known in the art, and are not redundantly described herein.
FIG. 2 is a schematic perspective view illustrating a paper-feeding mechanism of the automatic document feeder shown in FIG. 1. Please refer to FIGS. 1 and 2. The paper-feeding mechanism 11 comprises a pick-up module 111, a supporting module 112 and a stopper module 113. The pick-up module 111 comprises a pick-up roller 1111, a separation roller 1112 and a separation roller axle 1113. The separation roller 1112 is sheathed around a separation roller axle 1113, so that the separation roller 1112 is synchronously rotated with the separation roller axle 1113. The pick-up roller 1111 and the separation roller 1112 are connected with each other through a gear set, so that the pick-up roller 1111 is synchronously rotated with the separation roller 1112. The supporting module 112 has a sustaining part 1121. The stopper module 113 comprises a transmission rod 1131, a stopping slice 1132, a contact part 1133, a clamp part 1134 and a pivotal shaft 1135. The pick-up roller 1111 and the separation roller 1112 are disposed on the supporting module 112. The sustaining part 1121 of the supporting module 112 is also sheathed around the separation roller axle 1113. The pivotal shaft 1135 of the stopper module 113 is penetrated through the upper cover 10. As such, the stopper module 113 is connected to the upper cover 10, and the stopper module 113 is rotatable with respect to the upper cover 10 through the pivotal shaft 1135. The contact part 1133 is disposed at an end of the transmission rod 1131 and arranged in the vicinity of the sustaining part 1121. The clamp part 1134 is disposed at the other end of the transmission rod 1131 for clamping the stopping slice 1132. As such, the stopping slice 1132 is rotatable with respect to the transmission rod 1131.
In a case that the automatic document feeder 1 is disabled, the document D is stopped from being transported into the internal portion of the automatic document feeder 1 by the stopping slice 1132 (see FIG. 1). Whereas, in a case that the automatic document feeder 1 is enabled, the separation roller axle 1113 is driven and thus the pick-up roller 1111 and the separation roller 1112 are synchronously driven. In this situation, the pick-up roller 1111, the separation roller 1112 and the separation roller axle 1113 are rotated in the clockwise direction. Since the sustaining part 1121 is also sheathed around the separation roller axle 1113, the sustaining part 1121 is rotated in the clockwise direction. At this moment, the sustaining part 1121 is sustained against the contact part 1133 of the stopper module 113. As such, the transmission rod 1131 is rotated in the anti-clockwise direction by using the pivotal shaft 1135 as a rotating shaft. Since the transmission rod 1131 is pivotal about the pivotal shaft 1135, the stopping slice 1132 is uplifted vertically (see FIG. 3). Meanwhile, the document D placed on the paper input tray 14 can be transported into the internal portion of the automatic document feeder 1 without being stopped by the stopping slice 1132.
Although the conventional automatic document feeder 1 has a function of stopping the document D from entering the internal portion thereof when the automatic document feeder 1 is disabled, there are still has two problems. For example, since the stopping slice 1132 is moved in the vertical direction, the upper cover 10 of the automatic document feeder 1 is very high to allow the stopping slice 1132 to be moved vertically within the upper cover 10. In other words, the vertical movement of the stopping slice 1132 is detrimental to minimization of the automatic document feeder 1. Moreover, since the stopping slice 1132 is moved in the vertical direction, if the stopping slice 1132 is moved downwardly to be contact with the document D while the document D is transported across the region under the stopping slice 1132, the document D is readily destroyed by the stopping slice 1132. In this situation, a perforation will be formed in the document D. If the stopping slice 1132 is penetrated through the document D while the document D is transported across the region under the stopping slice 1132, the document D will be suffered from serious damage.